Inexpensive, Environmentally Benign Li-Ion Battery Cathode Materials for HEV and PHEV Applications

This project will develop inexpensive and environmentally benign LiMnPO4 cathodes for applications to lithium-ion batteries (LIB) used in electric and hybrid electric vehicles. This cathode material is expected to be far safer than Li-ion batteries employing traditional layered LiMO2 (M=Co, Ni) materials. A number of synthetic modifications will be pursued to optimize the LiMnPO4 material for use in Li-ion batteries: (1) decreasing the average particle size to a nano-region via sol-gel synthesis, thereby shortening the Li-ion diffusion path and ensuring the high rate performance of LiMnPO4 cathode materials; (2) doping with 1 atom percent of Nb5+ or Zr4+, which has proven successful in enhancing the electronic conductivity of LiFePO4 cathodes; and (3) adding conductive carbon nanoparticles during the sol-gel process, which also should increase the electronic conductivity of LiMnPO4 cathodes. In Phase I, cells will be tested for irreversible capacity, impedance, rate capability within varied temperature ranges, and self discharge rates. In-depth electrochemical characterizations of the best cathode candidate(s) will follow in Phase II, based on selected testing procedures of the DOE and the U.S. Advanced Battery Consortium. Commercial Applications and other Benefits as described by the awardee: Safe, inexpensive, and environmentally benign lithium-ion cells, with the high energy density and high-rate capability, should benefit the electric vehicle (EV) and hybrid electric vehicle (HEV) markets. Other niche markets include military man pack batteries and charging sources, aircraft applications, and specialized industrial applications.